Helical pipe-forming and welding apparatus method

ABSTRACT

Mechanism and procedure for joining, in the presence of heat and pressure, the abutting edges of a metal strip as it is formed helically into a length of cylindrical pipe. A welding head and pressure rollers are positioned at a joint-forming station to supply heat and pressure in proper amounts to insure formation of a continuous butt-welded seam in an uninterrupted edge-joining operation. The components of the mechanism are adjustable to adapt the mechanism to form pipe of varying sizes.



1. A method of forming helical pipe from an elongated metal strip, comprising: A. moving said strip longitudinally past a pipe-forming station, B. at said station coiling said strip into a continuous succession of hElical convolutions of predetermined diameter, C. deforming at least one marginal edge portion of said strip in the direction laterally inwardly of said strip, D. reforming said one edge portion in the direction laterally outwardly of said strip the distance of said deforming, into abutting engagement under lateral pressure with the other marginal edge portion, E. With said marginal edge portions so positioned, and under such lateral pressure, heating said edge portions to a temperature sufficient to weld the same together when pressure is applied thereto, and thereby joining the same together in nonoverlapped abutting engagement to provide therebetween a continuous butt-welded seam.
 2. deforming each of said edge portions slightly out of the regular contour of said strip whereby said edge surfaces are generally parallel as said edge portions are brought into said abutting engagement, and G. reforming said edge portions back into conformity with the regular contour of said strip when said lateral pressure is applied thereto during welding.
 2. A method of forming helical pipe form an elongated metal strip, comprising: A. moving said strip longitudinally past a pipe-forming station, B. at said station coiling said strip into a continuous succession of helical convolutions of predetermined diameter, C. bringing one marginal edge portion of said strip as the same is formed into said convolutions into abutting nonoverlapping engagement with the other marginal edge portion of said strip, D. heating said edge portions to a temperature sufficient to weld the same together when pressure is applied thereto, E. applying lateral pressure to said heated edge portions to join the same together in nonoverlapped abutting engagement to provide therebetween a continuous butt-welded seam, F. conditioning the edges of said marginal edge portions of said strip before moving the same to said station, including,
 2. means engaged with said roll assemblies which is responsive to a change in the feed angle of said strip to said station to automatically change the orientation of the wheels of said assemblies in proportion to the change of said feed angle.
 2. each of said structures being operatively engaged with said edge portions on opposite sides of said line of engagement therebetween,
 2. each of said structures being operatively engaged with said edge portions on opposite sides of said line of engagement therebetween,
 3. at least one of said structures comprising a pair of opposed cooperable roll portions engaged with and riding in the valley of the corrugation which is defined by the strip marginal edge portions being welded together,
 3. at least one of said structures including devices positioned to contact and urge said edge portions inwardly toward each other comprising a pair of laterally spaced rolls engaged with and riding generally upon the crests or corrugations positioned on opposite sides of said line of engagement along which said strip marginal edge portions are welded together.
 3. A method of forming helically corrugated pipe from an elongated metal strip having longitudinal corrugations extending therealong, comprising: A. uninterruptedly moving said corrugated strip past a pipe-forming station along a line defined by the longitudinal axis of said strip, B. at said station coiling said strip into a continuous succession of helical convolutions of predetermined diameter about a pipe axis which extends at an oblique angle relative to said strip axis, C. bringing the surface of one edge of said corrugated strip as the same is formed into said convolutions into abutting contact with the surface of the other edge of said strip, D. heating the marginal edge portions of said strip to an elevated temperature sufficient to weld the same together when pressure is applied thereto, and E. applying lateral pressure to said heated edge portions to join said surfaces together therebetween a continuous butt-welded seam without interrupting movement of said strip past said station.
 4. The method of claim 3, wherein A. said lateral pressure is effected by applying pressure to one side of the corrugations located on opposite sides of said one corrugation and to the opposite side of said edge portions, and, B. at said station said strip edge portions are joined so that together they define one helical corrugation of the completed pipe.
 4. said rOll portions lying on opposite sides of said line of engagement along which said edge portions are welded together.
 5. A method of forming helically corrugated pipe from an elongated metal strip having longitudinal corrugations extending therealong, comprising: A. uninterruptedly moving said corrugated strip past a pipe-forming station along a line defined by the longitudinal axis of said strip, B. at said station coiling said strip into a continuous succession of helical convolutions of predetermined diameter about a pipe axis which extends at an oblique angle relative to said strip axis, C. bringing tHe surface of one edge of said corrugated strip as the same is formed into said convolutions into abutting contact with the surface of the other edge of said strip, D. heating the marginal edge portions of said strip to an elevated temperature sufficient to weld the same together when pressure is applied thereto, E. applying lateral pressure to said heated edge portions to join said surfaces together in abutting engagement to provide therebetween a continuous butt-welded seam without interrupting movement of said strip past said station, F. locating said butt-welded seam so that said strip edge portions together define one helical corrugation of the completed pipe, and G. said lateral pressure being supplied to said edge portions in the valley of said one corrugation on opposite sides of the seam formed thereby.
 6. The method of claim 3 in which: said strip edge portions are heated by electrical current applied to said edge portions by welding contacts engaging said edge portions at said station slightly in advance of the point at which said edge portions come into engagement with each other.
 7. Apparatus for forming helically corrugated welded pipe from an elongated longitudinally corrugated metal strip, comprising: A. means for moving said strip past a station, B. means at said station for coiling said strip into a continuous succession of helical convolutions by bringing opposite marginal edge portions of said strip into abutting nonoverlapped engagement at a welding point, C. means at said station for heating said strip marginal edge portions to an elevated temperature sufficient to weld the same together in the presence of pressure, and, D. means for exerting lateral pressure to said heated edge portions to join the same together along the line of engagement therebetween to form a continuous nonoverlapped butt-welded seam extending helically around and along the pipe thus formed, said last named means including,
 8. Apparatus for forming helically corrugated welded pipe from an elongated longitudinally corrugated metal strip, comprising: A. means for moving said strip past a station, B. means at said station for coiling said strip into a continuous succession of helical convolutions by bringing opposite marginal edge portions of said strip into abutting nonoverlapped engagement at a welding point, C. means at said station for heating said strip marginal edge portions to an elevated temperature sufficient to weld the same together in the presence of pressure, and, D. means for exerting lateral pressure to said heated edge portions to join the same together along the line of engagement therebetween to form a continuous nonoverlapped butt-welded seam extending helically around and along the pipe thus formed, said last-named means including,
 9. The apparatus of claim 8 in which: said roll portions are mounted to rotate in planes which converge relative to each other so that lateral pressure is applied thereby to said edge portions.
 10. Apparatus for forming pipe from an elongated metal strip comprising: A. means for moving said strip past a station, B. means at said station for coiling said strip into a continuous succession of helical convolutions by bringing opposite marginal edge portions of said strip into abutting nonoverlapped engagement at a welding point, C. means at said station for heating said strip marginal edge portions to an elevated temperature sufficient to weld the same together in the presence of pressure, D. means for exerting lateral pressure to said heated edge portions to join the same together along the line of engagement therebetween to form a continuous nonoverlapped butt-welded seam extending helically around and along the pipe thus formed, E. means at said station for deforming at least one of said marginal edge portions out of the normal contour of said strip prior to movement of said marginal edge portions to said welding point, and F. means at said welding point for reforming said one marginal edge portion back to the normal contour of said strip.
 11. The apparatus of claim 10, including: means for forming the edge surfaces of said marginal edge portions into generally parallel relation as they approach said weld point.
 12. Apparatus for forming helically corrugated welded pipe from an elongated longitudinally corrugated metal strip, comprising: A. means for uninterruptedly moving said strip to and past a forming station, B. means at said station for coiling said strip into a continuous succession of helical convolutions by bringing opposite marginal edge portions of said strip into abutting nonoverlapped engagement,
 13. The apparatus of claim 12 in which said means engaged with said roll assemblies comprises: A. an apertured supporting plate, B. a slotted arm which is movable in response to a change in the feed angle of said strip, C. cam follower structures operatively engaged with said slotted arm, and D. connecting-pin structures extending through the apertures of said plate and interposed between said cam follower structures and the mounting structures for the wheels of said roll assemblies, E. movement of said slotted arm effecting corresponding movement of said cam follower structures to produce attendant movement of the wheels of said roll assemblies. 